Systolic pressure determining apparatus and process using integration to determine pulse amplitude
First Claim
1. In an apparatus for determining systolic pressure of a living test subject, said apparatus including means for applying a selectively changeable pressure to the test subject adjacent a blood vessel, means for measuring a fluctuating quantity proportional to a sum, said sum comprising a time-dependent fluctuating component proportional to the amplitude of the pulsatile pressure within the blood vessel plus the selectively changeable pressure applied externally adjacent the blood vessel, means for determining the maximum value attained by said fluctuating component as the applied pressure is changed, means for storing a representation of said maximum value, means for determining when said fluctuating component is substantially equal to about one half of said maximum value for an applied pressure greater than the pressure applied when said maximum value results, and means for reading out said applied pressure corresponding to said fluctuating component being substantially equal to a predetermined fraction of said maximum value, said readout pressure corresponding to the systolic pressure of said subject, the improvement comprising:
- means for converting said quantity into a representation of a time derivative of said fluctuating component thereof;
means for obtaining the time integral of said time derivative representation over an interval of predetermined limits in each of successive blood pressure pulses, said interval of integration extending substantially from the initiation of systolic rise to the systolic peak in respective blood pressure pulses, each said integral being proportional to the amplitude of said pulsatile pressure for the respective pulse; and
means for extending said time integral representations to said maximum value determining means.
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Abstract
In systolic pressure determining apparatus utilizing a pressure cuff and means for measuring a fluctuating quantity proportional to the sum of the cuff pressure and the fluctuating component proportioned to the pulsatile blood pressure, and including means for determining the maximum value of the fluctuating component as cuff pressure is varied, the improvement comprising means for converting the quantity into a representation of a time derivative of the fluctuating component means for obtaining the time integral of the time derivative over an interval of predetermined limits between initiation of systolic rise and systolic peak in each blood pressure pulse, and means extending the time integral, as a measure of pulse pressure amplitude, to the maximum value determining means. Specifically, certain crossings of a reference value by the time derivative are recognized as being the initiation of systolic rise and the systolic peak respectively, and the integration occurs over this interval.
The method implemented by the improved means also comprises an aspect of the invention.
29 Citations
9 Claims
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1. In an apparatus for determining systolic pressure of a living test subject, said apparatus including means for applying a selectively changeable pressure to the test subject adjacent a blood vessel, means for measuring a fluctuating quantity proportional to a sum, said sum comprising a time-dependent fluctuating component proportional to the amplitude of the pulsatile pressure within the blood vessel plus the selectively changeable pressure applied externally adjacent the blood vessel, means for determining the maximum value attained by said fluctuating component as the applied pressure is changed, means for storing a representation of said maximum value, means for determining when said fluctuating component is substantially equal to about one half of said maximum value for an applied pressure greater than the pressure applied when said maximum value results, and means for reading out said applied pressure corresponding to said fluctuating component being substantially equal to a predetermined fraction of said maximum value, said readout pressure corresponding to the systolic pressure of said subject, the improvement comprising:
means for converting said quantity into a representation of a time derivative of said fluctuating component thereof;
means for obtaining the time integral of said time derivative representation over an interval of predetermined limits in each of successive blood pressure pulses, said interval of integration extending substantially from the initiation of systolic rise to the systolic peak in respective blood pressure pulses, each said integral being proportional to the amplitude of said pulsatile pressure for the respective pulse; and
means for extending said time integral representations to said maximum value determining means.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a method for determining systolic pressure of a living test subject, including the steps comprising:
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applying a selectively changeable pressure to the test subject adjacent the blood vessel; measuring a quantity proportional to a sum, the sum comprising a time dependent fluctuating component proportional to the amplitude of the pulsatile pressure within the blood vessel plus the selectively changeable pressure applied externally adjacent the blood vessel; determining the maximum value attained by the fluctuating component as the applied pressure is changed; storing a representation of said maximum value; determining when said fluctuating component is substantially equal to a predetermined fraction of said maximum value for an applied pressure greater than the pressure applied when said maximum value results; and reading out the applied pressure corresponding to said fluctuating component being substantially equal to about one half of said maximum value, said readout pressure corresponding to the systolic pressure of said subject, the improvement comprising the steps of; converting said quantity proportional to said sum into a representation of a time derivative of said fluctuating component thereof; determining the time integral of said time derivative representation over an interval of predetermined limits in each of successive blood pressure pulses, said predetermined interval of integration extending substantially from the initiation of systolic rise to the systolic peak in respective blood pressure pulses, whereby the determined integral is proportional to the amplitude of the pulsatile pressure for the respective pulse; and using said time integral representations in said determination of the maximum value attained by said fluctuating component as the applied pressure is changed.
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Specification